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WO2018173646A1 - Système de communication - Google Patents

Système de communication Download PDF

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Publication number
WO2018173646A1
WO2018173646A1 PCT/JP2018/007132 JP2018007132W WO2018173646A1 WO 2018173646 A1 WO2018173646 A1 WO 2018173646A1 JP 2018007132 W JP2018007132 W JP 2018007132W WO 2018173646 A1 WO2018173646 A1 WO 2018173646A1
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WO
WIPO (PCT)
Prior art keywords
base station
mobile terminal
communication
transmission
stage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2018/007132
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English (en)
Japanese (ja)
Inventor
邦之 鈴木
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
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Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to CN201880017350.5A priority Critical patent/CN110431758A/zh
Priority to US16/484,899 priority patent/US10785661B2/en
Priority to EP18770534.8A priority patent/EP3605867A4/fr
Priority to CN202310155307.8A priority patent/CN116137545A/zh
Priority to EP23170358.8A priority patent/EP4236105A3/fr
Priority to JP2019507475A priority patent/JPWO2018173646A1/ja
Priority to CN202310166715.3A priority patent/CN116170045A/zh
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Publication of WO2018173646A1 publication Critical patent/WO2018173646A1/fr
Anticipated expiration legal-status Critical
Priority to US16/992,217 priority patent/US11483718B2/en
Priority to US17/941,143 priority patent/US20230007505A1/en
Priority to JP2022180092A priority patent/JP7499822B2/ja
Priority to US18/237,281 priority patent/US12137356B2/en
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/28—Cell structures using beam steering
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0626—Channel coefficients, e.g. channel state information [CSI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0628—Diversity capabilities
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0686—Hybrid systems, i.e. switching and simultaneous transmission
    • H04B7/0695—Hybrid systems, i.e. switching and simultaneous transmission using beam selection
    • H04B7/06952—Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping
    • H04B7/06964—Re-selection of one or more beams after beam failure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842—Weighted combining
    • H04B7/086—Weighted combining using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/046—Wireless resource allocation based on the type of the allocated resource the resource being in the space domain, e.g. beams
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/20—Manipulation of established connections
    • H04W76/27—Transitions between radio resource control [RRC] states

Definitions

  • the present invention relates to a communication system.
  • LTE Long Term Evolution
  • SAE System Architecture Evolution
  • OFDM Orthogonal Frequency Division Multiplexing
  • SC-FDMA Single Carrier Frequency Division Multiple Access
  • W-CDMA Wideband Code Division Multiple Access
  • Non-Patent Document 1 (Chapter 5), 3GPP determination items related to the frame configuration in the LTE system will be described with reference to FIG.
  • FIG. 1 is an explanatory diagram showing a configuration of a radio frame used in an LTE communication system.
  • one radio frame (Radio frame) is 10 ms.
  • the radio frame is divided into ten equally sized subframes.
  • the subframe is divided into two equally sized slots.
  • a downlink synchronization signal (Downlink Synchronization Signal) is included in the first and sixth subframes for each radio frame.
  • the synchronization signal includes a first synchronization signal (Primary Synchronization Signal: P-SS) and a second synchronization signal (Secondary Synchronization Signal: S-SS).
  • Non-Patent Document 1 (Chapter 5) describes the decision items regarding the channel configuration in the LTE system in 3GPP. It is assumed that the same channel configuration as that of the non-CSG cell is used in a CSG (Closed Subscriber Group) cell.
  • a physical broadcast channel (Physical Broadcast Channel: PBCH) is a communication terminal device such as a base station device (hereinafter simply referred to as “base station”) to a mobile terminal device (hereinafter also simply referred to as “mobile terminal”). It is a channel for downlink transmission to (hereinafter sometimes simply referred to as “communication terminal”).
  • a BCH transport block (transport block) is mapped to four subframes in a 40 ms interval. There is no obvious signaling of 40ms timing.
  • the physical control format indicator channel (Physical Control Format Indicator Channel: PCFICH) is a channel for downlink transmission from the base station to the communication terminal.
  • the PCFICH notifies the communication terminal of the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols used for PDCCHs.
  • PCFICH is transmitted for each subframe.
  • the physical downlink control channel (Physical Downlink Control Channel: PDCCH) is a channel for downlink transmission from the base station to the communication terminal.
  • the PDCCH includes resource allocation (allocation) information of a downlink shared channel (DL-SCH), which is one of transport channels described later, and a paging channel (Paging channel: PCH, one of transport channels described later). ) Resource allocation (allocation) information and HARQ (Hybrid Automatic Repeat reQuest) information related to DL-SCH.
  • the PDCCH carries an uplink scheduling grant (Uplink Scheduling Grant).
  • the PDCCH carries Ack (Acknowledgement) / Nack (Negative Acknowledgment) which is a response signal for uplink transmission.
  • the PDCCH is also called an L1 / L2 control signal.
  • a physical downlink shared channel is a channel for downlink transmission from a base station to a communication terminal.
  • a downlink shared channel (DL-SCH) that is a transport channel and PCH that is a transport channel are mapped.
  • the physical multicast channel (Physical Multicast Channel: PMCH) is a channel for downlink transmission from the base station to the communication terminal.
  • a multicast channel (Multicast Channel: MCH) that is a transport channel is mapped to the PMCH.
  • a physical uplink control channel (Physical Uplink Control Channel: PUCCH) is a channel for uplink transmission from a communication terminal to a base station.
  • the PUCCH carries Ack / Nack which is a response signal (response signal) for downlink transmission.
  • the PUCCH carries a CQI (Channel Quality Indicator) report.
  • CQI is quality information indicating the quality of received data or channel quality.
  • the PUCCH carries a scheduling request (SR).
  • SR scheduling request
  • the physical uplink shared channel (Physical Uplink Shared Channel: PUSCH) is a channel for uplink transmission from the communication terminal to the base station.
  • An uplink shared channel (Uplink Shared Channel: UL-SCH), which is one of the transport channels, is mapped to the PUSCH.
  • a physical HARQ indicator channel (Physical Hybrid ARQ Indicator Channel: PHICH) is a channel for downlink transmission from the base station to the communication terminal. PHICH carries Ack / Nack which is a response signal for uplink transmission.
  • a physical random access channel (Physical Random Access Channel: PRACH) is a channel for uplink transmission from a communication terminal to a base station. The PRACH carries a random access preamble.
  • the downlink reference signal (Reference Signal: RS) is a symbol known as an LTE communication system.
  • the following five types of downlink reference signals are defined.
  • Data demodulation reference signal (Demodulation Reference Signal: DM-RS) which is a cell-specific reference signal (Cell-specific Reference Signal: CRS), an MBSFN reference signal (MBSFN Reference Signal), and a mobile terminal specific reference signal (UE-specific Reference Signal).
  • Position determination reference signal Position determination reference signal
  • PRS Position determination reference signal
  • CSI-RS channel state information reference signal
  • RSRP reference signal received power
  • Non-Patent Document 1 (Chapter 5) will be described.
  • a broadcast channel (Broadcast Channel: BCH) is broadcast to the entire coverage of the base station (cell).
  • the BCH is mapped to the physical broadcast channel (PBCH).
  • PBCH physical broadcast channel
  • HARQ Hybrid ARQ
  • DL-SCH downlink shared channel
  • the DL-SCH can be broadcast to the entire coverage of the base station (cell).
  • DL-SCH supports dynamic or semi-static resource allocation. Quasi-static resource allocation is also referred to as persistent scheduling.
  • the DL-SCH supports discontinuous reception (DRX) of the communication terminal in order to reduce the power consumption of the communication terminal.
  • the DL-SCH is mapped to the physical downlink shared channel (PDSCH).
  • the paging channel supports DRX of the communication terminal in order to enable low power consumption of the communication terminal.
  • the PCH is required to be broadcast to the entire coverage of the base station (cell).
  • the PCH is mapped to a physical resource such as a physical downlink shared channel (PDSCH) that can be dynamically used for traffic.
  • PDSCH physical downlink shared channel
  • a multicast channel (Multicast Channel: MCH) is used for broadcasting to the entire coverage of a base station (cell).
  • the MCH supports SFN combining of MBMS (Multimedia Broadcast Multicast Service) services (MTCH and MCCH) in multi-cell transmission.
  • MTCH and MCCH Multimedia Broadcast Multicast Service
  • the MCH supports quasi-static resource allocation.
  • MCH is mapped to PMCH.
  • HARQ Hybrid ARQ
  • PUSCH physical uplink shared channel
  • Random Access Channel is limited to control information. RACH is at risk of collision.
  • the RACH is mapped to a physical random access channel (PRACH).
  • PRACH physical random access channel
  • HARQ is a technique for improving the communication quality of a transmission path by a combination of an automatic repeat request (Automatic Repeat reQuest: ARQ) and error correction (Forward Error Correction).
  • ARQ Automatic Repeat reQuest
  • error correction Forward Error Correction
  • HARQ has an advantage that error correction functions effectively by retransmission even for a transmission path whose communication quality changes. In particular, further quality improvement can be obtained by combining the initial transmission reception result and the retransmission reception result upon retransmission.
  • BCCH Broadcast Control Channel
  • BCH Broadcast Control Channel
  • DL-SCH downlink shared channel
  • the paging control channel (Paging Control Channel: PCCH) is a downlink channel for transmitting changes in paging information (Paging Information) and system information (System Information).
  • PCCH is used when the network does not know the cell location of the communication terminal.
  • the PCCH that is a logical channel is mapped to a paging channel (PCH) that is a transport channel.
  • PCH paging channel
  • the common control channel (Common Control Channel: CCCH) is a channel for transmission control information between the communication terminal and the base station. CCCH is used when the communication terminal does not have an RRC connection with the network.
  • CCCH is mapped to a downlink shared channel (DL-SCH) that is a transport channel.
  • DL-SCH downlink shared channel
  • UL-SCH uplink shared channel
  • the multicast control channel (Multicast Control Channel: MCCH) is a downlink channel for one-to-many transmission. MCCH is used for transmission of MBMS control information for one or several MTCHs from a network to a communication terminal. MCCH is used only for communication terminals receiving MBMS.
  • the MCCH is mapped to a multicast channel (MCH) that is a transport channel.
  • the dedicated control channel (Dedicated Control Channel: DCCH) is a channel for transmitting individual control information between the communication terminal and the network on a one-to-one basis.
  • the DCCH is used when the communication terminal is an RRC connection.
  • the DCCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink.
  • the dedicated traffic channel (Dedicated Traffic Channel: DTCH) is a channel for one-to-one communication to individual communication terminals for transmitting user information.
  • DTCH exists for both uplink and downlink.
  • the DTCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink.
  • UL-SCH uplink shared channel
  • DL-SCH downlink shared channel
  • a multicast traffic channel is a downlink channel for transmitting traffic data from a network to a communication terminal.
  • MTCH is a channel used only for communication terminals receiving MBMS.
  • the MTCH is mapped to a multicast channel (MCH).
  • CGI is a Cell Global Identifier.
  • ECGI is an E-UTRAN cell global identifier (E-UTRAN Cell Global Identifier).
  • LTE Long Term Evolution Advanced
  • UMTS Universal Mobile Telecommunication System
  • a CSG (Closed Subscriber Group) cell is a cell in which an operator identifies an available subscriber (hereinafter, may be referred to as a “specific subscriber cell”).
  • the identified subscribers are allowed to access one or more cells of the PLMN (Public Land Mobile Mobile Network).
  • PLMN Public Land Mobile Mobile Network
  • One or more cells to which the identified subscribers are allowed access are called “CSG cells (CSG cell (s))”.
  • CSG cell (s) Public Land Mobile Mobile Network
  • PLMN Public Land Mobile Mobile Network
  • the CSG cell is a part of a PLMN that broadcasts a unique CSG identity (CSG identity; CSG identity) and “TRUE” by CSG indication (CSG indication). Members of the subscriber group who have been registered in advance and permitted access the CSG cell using the CSG ID that is the access permission information.
  • CSG identity unique CSG identity
  • CSG indication CSG indication
  • the CSG ID is reported by the CSG cell or cell. There are multiple CSG IDs in an LTE communication system. The CSG ID is then used by the mobile terminal (UE) to facilitate access for CSG related members.
  • UE mobile terminal
  • the location tracking of communication terminals is performed in units of one or more cells.
  • the position tracking is performed to track the position of the communication terminal and call the communication terminal even in the standby state, in other words, to enable the communication terminal to receive a call.
  • This area for tracking the location of the communication terminal is called a tracking area.
  • Non-Patent Document 2 discloses three different modes of access to HeNB and HNB. Specifically, an open access mode (Open access mode), a closed access mode (Closed access mode), and a hybrid access mode (Hybrid access mode) are disclosed.
  • Open access mode Open access mode
  • closed access mode closed access mode
  • Hybrid access mode Hybrid access mode
  • LTE-A Long Term Evolution Advanced
  • Release 10 the Long Term Evolution Advanced (LTE-A) standard is being developed as Release 10 (see Non-Patent Document 3 and Non-Patent Document 4).
  • LTE-A is based on the LTE wireless communication system, and is configured by adding several new technologies.
  • CA Carrier aggregation
  • a mobile terminal When CA is configured, a mobile terminal has a network (Network: NW) and only one RRC connection (RRC connection). In the RRC connection, one serving cell provides NAS mobility information and security input. This cell is referred to as a primary cell (PCell).
  • PCell In the downlink, a carrier corresponding to PCell is a downlink primary component carrier (Downlink Primary Component Carrier: DL PCC).
  • DL PCC Downlink Primary Component Carrier
  • the carrier corresponding to the PCell in the uplink is an uplink primary component carrier (Uplink Primary Component Carrier: UL PCC).
  • a secondary cell (Secondary Cell: SCell) is configured to form a serving cell set together with the PCell.
  • the carrier corresponding to the SCell in the downlink is a downlink secondary component carrier (Downlink Secondary Component Carrier: DL SCC).
  • the carrier corresponding to the SCell in the uplink is an uplink secondary component carrier (Uplink Secondary Component Carrier: UL SCC).
  • a set of serving cells composed of one PCell and one or more SCells is configured for one mobile terminal.
  • Non-Patent Document 1 describes CoMP being studied for LTE-A by 3GPP.
  • the amount of mobile network traffic is increasing and the communication speed is increasing.
  • the communication speed is expected to be further increased.
  • a small eNB (hereinafter sometimes referred to as a “small base station apparatus”) that constitutes a small cell.
  • a technology for increasing frequency utilization efficiency and increasing communication capacity by installing a large number of small eNBs and configuring a large number of small cells has been studied.
  • dual connectivity abbreviation: DC
  • Non-Patent Document 1 describes DC.
  • eNBs that perform dual connectivity (DC)
  • master eNB abbreviation: MeNB
  • secondary eNB abbreviation: SeNB
  • 5G fifth-generation wireless access system aimed at starting service after 2020 for mobile communication that is becoming more sophisticated is being studied.
  • 5G requirements are compiled by an organization called METIS (see Non-Patent Document 5).
  • the system capacity is 1000 times
  • the data transmission speed is 100 times
  • the data processing delay is 1/10 (1/10)
  • the simultaneous connection number of communication terminals is 100 times that of the LTE system.
  • MIMO Multiple Input Input Multiple Output
  • the 5G wireless access system is considered to be mixed with the LTE system at the beginning of the service scheduled for 2020.
  • An LTE base station and a 5G base station are connected in a DC configuration, the LTE base station is a MeNB, and the 5G base station is a SeNB, so that the LTE base station with a large cell range processes C-plane data, and the LTE base station A configuration in which a U-plane process is performed between a station and a 5G base station is considered.
  • a mobile terminal Since a large capacity communication is a necessary condition in the 5G system, it is considered that a mobile terminal forms a beam with super multi-element antennas having more than eight elements.
  • a method of forming a beam in two stages is known in order to reduce the processing amount.
  • the first stage a plurality of basic beams with reduced directivity are formed, and in the second stage, SN improvement or null (null) formation is performed using the first stage beam.
  • the following two methods are being studied.
  • One method is a hybrid method in which the first stage forms an analog beam and the second stage forms a digital beam. According to the hybrid system, processing of the digital unit can be reduced.
  • Another method is a full digital method in which the number of beams in the first stage is reduced to the number that can be processed, and the first stage forms a beam digitally. According to the full digital method, analog variations such as frequency characteristics can be eliminated.
  • the present invention aims to provide a technique capable of ensuring good communication quality with respect to the above-mentioned problems.
  • the present invention provides, for example, a communication procedure required between a mobile terminal and a base station to specifically form a beam in the mobile terminal, thereby ensuring good communication quality. Make it possible.
  • the present invention provides, for example, a technique for forming a first-stage basic beam of a mobile terminal by a beam that does not interfere with another base station that is different from the target base station with which communication is desired. Even if the base station does not consider interference of other base stations, it is possible to ensure good communication quality.
  • a first communication system of the present invention is a communication system comprising a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication, wherein the mobile terminal performs radio communication using a beam,
  • the mobile terminal detects a beam lost state in which the communication quality with the base station cannot be maintained, the mobile terminal notifies the beam lost state by a beam having a wider half-value width than before the beam lost state is detected.
  • Send is a communication system comprising a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication, wherein the mobile terminal performs radio communication using a beam, When the mobile terminal detects a beam lost state in which the communication quality with the base station cannot be maintained, the mobile terminal notifies the beam lost state by a beam having a wider half-value width than before the beam lost state is detected.
  • Send is a communication system comprising a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication, wherein the mobile terminal performs
  • a second communication system of the present invention is a communication system comprising a mobile terminal and a base station connected to the mobile terminal so as to be capable of wireless communication, wherein the mobile terminal performs radio communication using a beam,
  • the mobile terminal When the mobile terminal detects a beam lost state in which communication quality cannot be maintained with the first base station, the mobile terminal configures dual connectivity with the first base station to notify the beam lost state.
  • the second base station To the second base station, and when the second base station receives the notification that the beam is lost, the second base station communicates with the mobile terminal with respect to the first base station. Is instructed to perform the beam redetection process.
  • a third communication system of the present invention is a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform radio communication, and the mobile terminal uses a multi-element antenna in two stages. Wireless communication is performed using a beam forming method, and the mobile terminal transmits information for identifying the attribute of each beam in the first stage to the base station.
  • a fourth communication system of the present invention is a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform radio communication, wherein the mobile terminal communicates with the first base station.
  • the mobile terminal measures the degree of interference exerted by the second base station on the transmission signal from the first base station, and determines the measurement result as the first base station.
  • the first base station changes the transmission power of the signal to be transmitted to the mobile terminal based on the received measurement result.
  • a fifth communication system of the present invention is a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform radio communication, wherein the mobile terminal communicates with the first base station.
  • the first base station When the first base station does not communicate with the second base station, the first base station suppresses interference between data transmission from the first base station to the mobile terminal and data transmission by the second base station. And the second base station is requested to transmit data according to the adjusted communication condition.
  • a sixth communication system of the present invention is a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication, and the mobile terminal uses a multi-element antenna to perform two steps.
  • wireless communication is performed by a beam forming method and the mobile terminal communicates with the first base station but does not communicate with the second base station, the mobile terminal transmits a main beam to the first base station.
  • a beam directed null toward the second base station and at least one beam directed null toward the second base station are formed as first stage beams.
  • a seventh communication system of the present invention is a communication system comprising a mobile terminal and a base station that is connected to the mobile terminal so as to be able to perform radio communication, and the mobile terminal uses a multi-element antenna in two stages.
  • wireless communication is performed by a beam forming method, and the mobile terminal communicates with the first base station but does not communicate with the second base station, the mobile terminal transmits the multipath direction of the first base station.
  • at least one beam whose main beam is directed toward the second base station is designed by adjusting the set number of multipaths, and the designed beam is formed as the first stage beam.
  • An eighth communication system of the present invention is a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication, and the mobile terminal uses reversibility of a transmission path. It is configured to be able to perform reversible utilization transmission path estimation, which is transmission path estimation, for each frequency band, and the mobile terminal determines whether to perform reversible utilization transmission path estimation for each frequency band. Reversibility supportability information is transmitted to the base station, and based on the reversibility supportability information of the mobile terminal, both the mobile terminal and the base station transmit the reversibility use transmission. In a frequency band where path estimation can be performed, communication with the mobile terminal is performed using the reversible transmission path estimation.
  • FIG. 2 is an explanatory diagram showing a configuration of a radio frame used in an LTE communication system.
  • 1 is a block diagram showing an overall configuration of an LTE communication system 200 discussed in 3GPP.
  • FIG. It is a block diagram which shows the structure of the mobile terminal 202 shown in FIG. 2 which is a communication terminal which concerns on this invention.
  • It is a block diagram which shows the structure of the base station 203 shown in FIG. 2 which is a base station which concerns on this invention.
  • 5 is a flowchart illustrating an outline from a cell search to a standby operation performed by a mobile terminal (UE) in an LTE communication system.
  • FIG. 1 is a block diagram showing an overall configuration of an LTE communication system 200 discussed in 3GPP.
  • FIG. It is a block diagram which shows the structure of the mobile terminal 202 shown in FIG. 2 which is a communication terminal which concerns on this invention.
  • It is a block
  • FIG. 3 is a diagram for explaining a method of forming a beam in two stages in the first embodiment. It is a figure explaining the other method of forming a beam in two steps about Embodiment 1.
  • FIG. FIG. 6 is a sequence diagram for explaining a first example of re-acquisition when a beam disappears in the first embodiment (when a mobile terminal performs beam detection).
  • FIG. 10 is a sequence diagram for explaining a second example of re-acquisition when a beam disappears in the first embodiment (when both a mobile terminal and a base station perform beam detection).
  • FIG. 11 is a sequence diagram for explaining a third example of re-acquisition when a beam disappears in the first embodiment (in the case of dual-connectivity).
  • FIG. 10 is a diagram illustrating a first example in which nine beams are formed as first-stage beams in the second embodiment.
  • FIG. 10 is a diagram illustrating a second example in which nine beams are formed as the first stage beam in the second embodiment.
  • FIG. 10 is a diagram illustrating a third example in which nine beams are formed as first-stage beams in the second embodiment.
  • FIG. 9 is a diagram for explaining an antenna in which a plurality of basic elements (dipole antennas and the like) are arranged in a circle according to the second embodiment.
  • FIG. 10 is a diagram for explaining beam directivity in two-stage beam formation in the third embodiment.
  • FIG. 10 is a sequence diagram illustrating an example in which the setting of whether or not to support reversibility for each frequency band is performed at the time of channel setting in the fourth embodiment.
  • FIG. 16 is a sequence diagram illustrating an example in which the setting of whether or not to support reversibility for each frequency band is performed at the time of handover in the fourth embodiment.
  • FIG. 16 is a sequence diagram illustrating an example in which the setting of whether or not to support reversibility for each frequency band is performed at the time of handover in the fourth embodiment.
  • FIG. FIG. 2 is a block diagram showing an overall configuration of an LTE communication system 200 discussed in 3GPP.
  • the radio access network is referred to as E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201.
  • a mobile terminal device hereinafter referred to as “user equipment (UE)”
  • UE user equipment
  • base station E-UTRAN NodeB: eNB
  • signals are transmitted and received by wireless communication.
  • the “communication terminal device” includes not only a mobile terminal device such as a movable mobile phone terminal device but also a non-moving device such as a sensor.
  • the “communication terminal device” may be simply referred to as “communication terminal”.
  • Control protocols for the mobile terminal 202 such as RRC (Radio Resource Control) and user planes such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical Layer)
  • RRC Radio Resource Control
  • PDCP Packet Data Convergence Protocol
  • RLC Radio Link Control
  • MAC Medium Access Control
  • PHY Physical Layer
  • a control protocol RRC (Radio Resource Control) between the mobile terminal 202 and the base station 203 performs broadcast, paging, RRC connection management (RRC connection management), and the like. As states of the base station 203 and the mobile terminal 202 in RRC, there are RRC_IDLE and RRC_CONNECTED.
  • RRC_IDLE PLMN (Public Land Mobile Mobile Network) selection, system information (System Information: SI) notification, paging, cell re-selection, mobility, and the like are performed.
  • RRC_CONNECTED the mobile terminal has an RRC connection and can send and receive data to and from the network.
  • handover Handover: HO
  • measurement of neighbor cells neighborhbour cells
  • the base station 203 is classified into an eNB 207 and a Home-eNB 206.
  • the communication system 200 includes an eNB group 203-1 including a plurality of eNBs 207 and a Home-eNB group 203-2 including a plurality of Home-eNBs 206.
  • a system composed of EPC (Evolved Packet Core) as a core network and E-UTRAN 201 as a radio access network is referred to as EPS (Evolved Packet System).
  • EPS Evolved Packet System
  • the EPC that is the core network and the E-UTRAN 201 that is the radio access network may be collectively referred to as “network”.
  • the eNB 207 includes a mobility management entity (Mobility Management Entity: MME), an S-GW (Serving Management Gateway), or an MME / S-GW unit including the MME and S-GW (hereinafter, also referred to as “MME unit”) 204.
  • MME mobility management entity
  • S-GW Serving Management Gateway
  • MME / S-GW unit including the MME and S-GW
  • the control information is communicated between the eNB 207 and the MME unit 204 through the S1 interface.
  • a plurality of MME units 204 may be connected to one eNB 207.
  • the eNBs 207 are connected by the X2 interface, and control information is communicated between the eNBs 207.
  • the Home-eNB 206 is connected to the MME unit 204 via the S1 interface, and control information is communicated between the Home-eNB 206 and the MME unit 204.
  • a plurality of Home-eNBs 206 are connected to one MME unit 204.
  • the Home-eNB 206 is connected to the MME unit 204 via a HeNBGW (Home-eNB GateWay) 205.
  • the Home-eNB 206 and the HeNBGW 205 are connected via the S1 interface, and the HeNBGW 205 and the MME unit 204 are connected via the S1 interface.
  • One or more Home-eNBs 206 are connected to one HeNBGW 205, and information is communicated through the S1 interface.
  • the HeNBGW 205 is connected to one or a plurality of MME units 204, and information is communicated through the S1 interface.
  • the MME unit 204 and the HeNBGW 205 are higher-level devices, specifically higher-level nodes, and control the connection between the eNB 207 and Home-eNB 206, which are base stations, and the mobile terminal (UE) 202.
  • the MME unit 204 constitutes an EPC that is a core network.
  • the base station 203 and the HeNBGW 205 constitute an E-UTRAN 201.
  • the X2 interface between Home-eNB 206 is supported. That is, the Home-eNB 206 is connected by the X2 interface, and control information is communicated between the Home-eNB 206. From the MME unit 204, the HeNBGW 205 appears as a Home-eNB 206. From the Home-eNB 206, the HeNBGW 205 appears as the MME unit 204.
  • the interface between the Home-eNB 206 and the MME unit 204 is an S1 interface. The same.
  • the base station 203 may configure one cell or a plurality of cells. Each cell has a predetermined range as a coverage that is a range in which communication with the mobile terminal 202 is possible, and performs wireless communication with the mobile terminal 202 within the coverage. When one base station 203 forms a plurality of cells, each cell is configured to be able to communicate with the mobile terminal 202.
  • FIG. 3 is a block diagram showing a configuration of the mobile terminal 202 shown in FIG. 2, which is a communication terminal according to the present invention.
  • the transmission process of the mobile terminal 202 shown in FIG. 3 will be described.
  • control data from the protocol processing unit 301 and user data from the application unit 302 are stored in the transmission data buffer unit 303.
  • the data stored in the transmission data buffer unit 303 is transferred to the encoder unit 304 and subjected to encoding processing such as error correction.
  • the data encoded by the encoder unit 304 is modulated by the modulation unit 305.
  • the modulated data is converted into a baseband signal, and then output to the frequency conversion unit 306, where it is converted into a radio transmission frequency.
  • a transmission signal is transmitted from the antenna 307 to the base station 203.
  • the reception process of the mobile terminal 202 is executed as follows.
  • a radio signal from the base station 203 is received by the antenna 307.
  • the received signal is converted from a radio reception frequency to a baseband signal by the frequency converter 306, and demodulated by the demodulator 308.
  • the demodulated data is transferred to the decoder unit 309 and subjected to decoding processing such as error correction.
  • control data is passed to the protocol processing unit 301, and user data is passed to the application unit 302.
  • a series of processing of the mobile terminal 202 is controlled by the control unit 310. Therefore, although not shown in FIG. 3, the control unit 310 is connected to the units 301 to 309.
  • FIG. 4 is a block diagram showing a configuration of the base station 203 shown in FIG. 2, which is a base station according to the present invention.
  • the transmission process of the base station 203 shown in FIG. 4 will be described.
  • the EPC communication unit 401 transmits and receives data between the base station 203 and the EPC (such as the MME unit 204) and the HeNBGW 205.
  • the other base station communication unit 402 transmits / receives data to / from other base stations.
  • the EPC communication unit 401 and the other base station communication unit 402 exchange information with the protocol processing unit 403, respectively. Control data from the protocol processing unit 403 and user data and control data from the EPC communication unit 401 and the other base station communication unit 402 are stored in the transmission data buffer unit 404.
  • the data stored in the transmission data buffer unit 404 is passed to the encoder unit 405 and subjected to encoding processing such as error correction. There may exist data directly output from the transmission data buffer unit 404 to the modulation unit 406 without performing the encoding process.
  • the encoded data is subjected to modulation processing by the modulation unit 406.
  • the modulated data is converted into a baseband signal and then output to the frequency conversion unit 407 where it is converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 408 to one or a plurality of mobile terminals 202.
  • the reception processing of the base station 203 is executed as follows. Radio signals from one or more mobile terminals 202 are received by the antenna 408. The received signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 407, and demodulated by the demodulation unit 409. The demodulated data is transferred to the decoder unit 410 and subjected to decoding processing such as error correction. Of the decoded data, control data is passed to the protocol processing unit 403 or EPC communication unit 401 and other base station communication unit 402, and user data is passed to the EPC communication unit 401 and other base station communication unit 402. A series of processing of the base station 203 is controlled by the control unit 411. Therefore, although not shown in FIG. 4, the control unit 411 is connected to the units 401 to 410.
  • FIG. 5 is a block diagram showing the configuration of the MME according to the present invention.
  • FIG. 5 shows the configuration of the MME 204a included in the MME unit 204 shown in FIG.
  • the PDN GW communication unit 501 transmits and receives data between the MME 204a and the PDN GW.
  • the base station communication unit 502 performs data transmission / reception between the MME 204a and the base station 203 using the S1 interface.
  • the data received from the PDN GW is user data
  • the user data is passed from the PDN GW communication unit 501 to the base station communication unit 502 via the user plane communication unit 503 and to one or more base stations 203.
  • Sent When the data received from the base station 203 is user data, the user data is passed from the base station communication unit 502 to the PDN GW communication unit 501 via the user plane communication unit 503 and transmitted to the PDN GW.
  • control data is passed from the PDN GW communication unit 501 to the control plane control unit 505.
  • control data is transferred from the base station communication unit 502 to the control plane control unit 505.
  • the HeNBGW communication unit 504 is provided when the HeNBGW 205 exists, and performs data transmission / reception through an interface (IF) between the MME 204a and the HeNBGW 205 depending on the information type.
  • the control data received from the HeNBGW communication unit 504 is passed from the HeNBGW communication unit 504 to the control plane control unit 505.
  • the processing result in the control plane control unit 505 is transmitted to the PDN GW via the PDN GW communication unit 501.
  • the result processed by the control plane control unit 505 is transmitted to one or more base stations 203 via the S1 interface via the base station communication unit 502, and to one or more HeNBGWs 205 via the HeNBGW communication unit 504. Sent.
  • the control plane control unit 505 includes a NAS security unit 505-1, an SAE bearer control unit 505-2, an idle state mobility management unit 505-3, and the like, and performs overall processing for the control plane.
  • the NAS security unit 505-1 performs security of a NAS (Non-Access Stratum) message.
  • the SAE bearer control unit 505-2 performs management of SAE (System Architecture) Evolution bearers and the like.
  • the idle state mobility management unit 505-3 performs mobility management in a standby state (idle state; also referred to as LTE-IDLE state or simply idle), generation and control of a paging signal in the standby state,
  • the tracking area of one or a plurality of mobile terminals 202 is added, deleted, updated, searched, and tracking area list is managed.
  • the MME 204a distributes the paging signal to one or a plurality of base stations 203. Further, the MME 204a performs mobility control (Mobility control) in a standby state (Idle State). The MME 204a manages a tracking area list when the mobile terminal is in a standby state and in an active state (Active State). The MME 204a starts a paging protocol by transmitting a paging message to a cell belonging to a tracking area (tracking area: TrackingTrackArea) where the UE is registered. Management of the CSG of the Home-eNB 206 connected to the MME 204a, management of the CSG ID, and management of the white list may be performed by the idle state mobility management unit 505-3.
  • FIG. 6 is a flowchart illustrating an outline from a cell search to a standby operation performed by a communication terminal (UE) in an LTE communication system.
  • the communication terminal uses the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from the neighboring base stations in step ST601, and performs slot timing, frame Synchronize timing.
  • P-SS first synchronization signal
  • S-SS second synchronization signal
  • the P-SS and S-SS are collectively referred to as a synchronization signal (SS).
  • SS synchronization signal
  • a synchronization code corresponding to one-to-one is assigned to the PCI assigned to each cell.
  • 504 patterns are under consideration. Synchronization is performed using the 504 PCIs, and the PCI of the synchronized cell is detected (specified).
  • a cell-specific reference signal that is a reference signal (reference signal: RS) transmitted from the base station to each cell is detected for the synchronized cell.
  • Measure the received power of RS Reference Signal Received Power: RSRP.
  • RS Reference Signal Received Power
  • RS Reference Signal
  • a code corresponding to PCI one to one is used. By correlating with that code, it can be separated from other cells.
  • deriving the RS code of the cell from the PCI specified in step ST601 it is possible to detect the RS and measure the received power of the RS.
  • a cell having the best RS reception quality for example, a cell having the highest RS reception power, that is, the best cell is selected from one or more cells detected in step ST602.
  • step ST604 the PBCH of the best cell is received and the BCCH that is broadcast information is obtained.
  • MIB Master Information Block
  • the MIB information includes, for example, DL (downlink) system bandwidth (also called transmission bandwidth setting (transmission bandwidth configuration: dl-bandwidth)), the number of transmission antennas, SFN (System frame number), and the like.
  • SIB1 includes information related to access to the cell, information related to cell selection, and scheduling information of other SIBs (SIBk; an integer of k ⁇ 2).
  • SIB1 includes a tracking area code (TrackingTrackArea Code: TAC).
  • the communication terminal compares the TAC of SIB1 received in step ST605 with the TAC portion of the tracking area identifier (Tracking Area Identity: TAI) in the tracking area list already held by the communication terminal.
  • the tracking area list is also referred to as a TAI list (TAI list).
  • TAI is identification information for identifying a tracking area, and is composed of MCC (Mobile Country Code), MNC (Mobile Network Code), and TAC (Tracking Area Code).
  • MCC Mobile Country Code
  • MNC Mobile Network Code
  • TAC Track Area Code
  • MCC Mobile Country Code
  • MNC Mobile Network Code
  • TAC Track Area Code
  • step ST606 If, as a result of the comparison in step ST606, the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters a standby operation in the cell. In comparison, if the TAC received in step ST605 is not included in the tracking area list, the communication terminal passes through the cell to a core network (Core Network, EPC) including MME and the like, and TAU (Tracking Area Update). Request tracking area change to do
  • EPC Core Network, EPC
  • MME Mobile Management Entity
  • TAU Track Area Update
  • a device that constitutes a core network performs tracking based on the identification number (UE-ID, etc.) of the communication terminal sent from the communication terminal together with the TAU request signal. Update the area list.
  • the core network side device transmits the updated tracking area list to the communication terminal.
  • the communication terminal rewrites (updates) the TAC list held by the communication terminal based on the received tracking area list. Thereafter, the communication terminal enters a standby operation in the cell.
  • the following relates to a technique for maintaining communication by changing the basic beam in accordance with, for example, a change in communication status.
  • One method is a method of forming a beam by providing AD (Analog-to-Digital Converter) and DA (Digital-to-Analog Converter) for each antenna element. Since the antenna gain is low, it is difficult to ensure calculation accuracy. In addition, it is known that the calculation for improving the signal-to-noise ratio (Signal-to-Noise) and the calculation for forming the beam null increase on the order of the cube of the number of elements. Various studies are required. Hereinafter, the SN ratio may be referred to as SN.
  • a method of forming a beam in two stages is known.
  • the directivity variable antenna when the same signal is radiated from the elements of each antenna in the same phase, a signal whose directivity is narrowed in a direction perpendicular to the radiation surface (directly in front) can be transmitted.
  • the phase of the same signal emitted from each element is adjusted to be the distance between each element ⁇ sin ⁇ , a beam whose transmission direction (that is, directivity) is shifted by ⁇ can be formed.
  • SN can be improved and calculation accuracy can be increased.
  • the amount of computation for forming null using the first stage beam can be reduced in the second stage. See FIG.
  • Another method is to form a plurality of antenna elements with analog in the first stage and perform desired beam formation.
  • the first-stage analog beam is formed with a beam with reduced directivity by using, for example, a horn antenna or a sector antenna, or by changing the phase in an analog manner.
  • the second stage is a hybrid system that digitally forms the first stage beam in the same manner as the above-described first eye system. See FIG.
  • the mobile terminal uses the first stage beam (n beams) of the mobile terminal and uses the first stage beam of the base station.
  • n beams the known sequence data transmitted in (m beams)
  • an n ⁇ m transmission path is estimated.
  • diversity and equalization processing are performed using the estimated transmission path to improve throughput.
  • it is effective to form the second-stage beam by multiplying the transmission data of the mobile terminal by the inverse characteristic of the n ⁇ m transmission path as a precoding weight.
  • This weight calculation can be executed by, for example, calculating an inverse matrix of an n ⁇ m transmission path matrix.
  • Embodiment 1 solves the above problem.
  • the following relates to re-acquisition when the beam disappears, for example.
  • the first stage beam of the mobile terminal should cover the entire area with multiple first stage beams.
  • the directivity cannot be narrowed down to a desired direction, and the antenna gain cannot be obtained. Therefore, it is effective to direct the directivity in the direction of the opposing base station.
  • it is effective to direct the directivity in the direction in which the signal from the base station arrives directly or in the direction in which the signal arrives while being reflected or diffracted.
  • it is effective to direct the first stage beam to all base stations and repeaters that are transmitting PSS (Primary Synchronization Signal) or SSS (Secondary Synchronization Signal). .
  • PSS Primary Synchronization Signal
  • SSS Secondary Synchronization Signal
  • the mobile terminal intermittently transmits a known sequence signal corresponding to a signal called sounding so that the base station can monitor fluctuations in the transmission path.
  • This signal is transmitted with directivity of the first stage beam.
  • the mobile terminal may change the beam directivity during the non-communication time, and sequentially monitor the surrounding space for whether the transmission path is changed due to movement or the like.
  • the received signal of the known sequence data from the opposite base station disappears or becomes weak.
  • the terminal detects a change in the transmission path.
  • SN is smaller than a certain threshold and a change in the transmission path is detected, if communication is in progress, data communication / sounding communication is stopped, and the entire space is monitored using the time zone scheduled for data communication.
  • a first stage beam may be formed toward the base station and a sounding signal may be transmitted.
  • the multiple antennas corresponding to the multiple antennas of the mobile terminal are directed in that direction. Since different data can be sent and received simultaneously, it is effective.
  • Fig. 9 shows a detailed example of the processing flow.
  • the mobile terminal and the base station perform the beam detection procedure St901 when initial synchronization is established.
  • the base station notifies the broadcast information of what frequency, timing, and code (spreading code seed, etc.) the beam for random access is formed on.
  • the mobile terminal receives the broadcast information and performs a neighbor cell / beam search based on the received broadcast information to monitor what transmission path each beam of the base station is between each beam of the mobile terminal. Then, ordering is performed from a transmission line with good quality.
  • the mobile terminal and the base station perform a communication establishment procedure St902.
  • the mobile terminal transmits a channel setting request using a random access channel or the like to a base station that can be accepted among the base station beams found in St901.
  • the mobile terminal transmits a channel setting request to the above-acceptable base station with the directivity of the second-stage beam obtained by combining the first-stage beams of the mobile terminal and enhancing the directivity.
  • the mobile terminal transmits a channel setting request in accordance with the base station beam resources (frequency, timing, and code (spreading code seed, etc.)).
  • the directivity (half-value width) of random access is adjusted in accordance with the speed of the peripheral monitoring cycle of the mobile terminal, it is possible to cope with changes in the propagation environment and improve the possibility of establishing communication.
  • the normal half-width is A (°)
  • the peripheral monitoring period of the mobile terminal is C (ms)
  • the speed of change in the propagation environment due to movement of the mobile terminal is determined by the mobile terminal.
  • the average time of 3 dB variation by averaging is D (ms)
  • the flow after the procedure St903 is a flow when the received signal of the known sequence data (DMRS or CSI-RS) from the opposite base station is lost or weakened due to, for example, the change of the direction of the mobile terminal. is there.
  • DMRS known sequence data
  • CSI-RS CSI-RS
  • step St903 the mobile terminal performs normal communication and SN measurement of each beam in parallel.
  • the mobile terminal monitors the known sequence of the first stage beam, and when the known sequence is transmitted with the directivity of the second stage beam The known series of the second stage beam is monitored. The SN is measured by a known series monitor.
  • DMRS / CSI-RS transmitted with the directivity of the second-stage beam is monitored.
  • step St904 the mobile terminal determines whether or not all SNs of the second-stage beam used for communication are below a certain threshold that can maintain communication quality.
  • the mobile terminal Continue St903.
  • the mobile terminal stops data communication / sounding communication and transmits a beam loss notification if the communication is in progress (step St905). It is desirable to transmit the beam loss notification using dedicated / shared channels (PUSCH / PUCCH) in order to simplify the state transition of communication. Alternatively, since it is important that communication is not disconnected, random access may be used for the beam loss notification. Alternatively, since it is important not to disconnect the communication, from the viewpoint of beam directivity (half-value width), it is also effective to transmit a beam loss notification by maximizing the half-value width or by setting the beam as an omni beam. is there.
  • PUSCH / PUCCH dedicated / shared channels
  • the mobile terminal starts the beam redetection procedure St906 while waiting for a response to the beam disappearance notification.
  • it is also effective to continue the data communication with the base station by setting the full width at half maximum or setting the beam as an omni beam. Even if the direction of the base station is lost, if it is an omni beam, communication can be expected to continue by slowing the transmission rate.
  • the transmission path quality between the beams can be quickly restored by transmitting the beam loss notification from the mobile terminal.
  • FIG. 10 shows an example in which beam detection is performed at the base station in addition to the mobile terminal.
  • the flow in FIG. 10 is obtained by adding a procedure in the base station to the flow in FIG. 9, and the same reference numerals are used for the above-described procedures, and the duplicate description is omitted.
  • the mobile terminal cannot send a beam to the dark cloud when it cannot identify the beam. Even if the mobile terminal cannot detect the beam for a short time, it is also effective to wait for a while on the base station side, considering that the transmission path is immediately restored. For example, this is the case when a truck runs through between a mobile terminal and a base station. Therefore, the base station measures the SN of each beam while performing normal communication in St903b, similarly to the procedure St903 in the mobile terminal, and in St904b, all the two stages for the mobile terminal are performed in the same manner as the procedure St904 in the mobile terminal. It is determined whether or not the SN of the eye beam is equal to or lower than a certain threshold that can maintain the communication quality.
  • the base station If the SNs of all the second stage beams are equal to or less than the threshold value, the base station starts a timer for waiting for the start of the beam redetection procedure in step St907. If a beam exceeding the threshold value is not obtained a predetermined number of times, a time-out occurs (see the loops of procedures St908, St903b, St904b, and St907), and the base station executes the beam redetection procedure St906.
  • step St904b if the condition that the SNs of all the second stage beams are not more than the threshold value is not satisfied, that is, if at least one SN of the second stage beam is larger than the threshold value, the base station determines the procedure St909. In step S903, the timer is cleared, and the process returns to step St903b.
  • the base station can autonomously start the beam redetection procedure.
  • time-out occurs with the number of times that the condition of ⁇ SN of all second stage beams ⁇ ⁇ threshold ⁇ is satisfied in St904b. Instead, it is also effective to start a timer at the base station and time out after elapse of a predetermined time.
  • the time until timeout may be defined from a host device such as OAM (Operation Administration and Maintenance), or may be stored in a nonvolatile memory as an activation parameter of the base station.
  • OAM Operaation Administration and Maintenance
  • FIG. 11 shows another example of the processing flow.
  • the flow in FIG. 11 is obtained by adding the procedure in the MeNB to the flow in FIG. 9, and the same reference numerals are used for the above-described procedures, and the duplicate description is omitted.
  • FIG. 11 relates to a case where the base station performs dual-connectivity and handles a common channel only in the MeNB.
  • the mobile terminal when it is determined in step St904 that the mobile terminal becomes ⁇ SN of all second-stage beams ⁇ ⁇ threshold ⁇ , the mobile terminal notifies the beam disappearance notification in step St1001, and the communicating SeNB And send to MeNB. At this time, the mobile terminal transmits a beam loss notification to the MeNB using an omni beam.
  • the MeNB receives the beam disappearance notification, the MeNB notifies the SeNB of a beam redetection instruction in step St1002. Thereby, the beam redetection procedure St906 is started.
  • the transmission path quality between the beams can be recovered early even if the mobile terminal cannot detect the beam. It becomes possible.
  • the mobile terminal if the response of the beam loss notification is returned from the base station to the mobile terminal with an omni beam or a beam with the maximum half-value width, the mobile terminal repeatedly transmits the beam loss notification. It can be stopped. As a result, the efficiency of the total radio resources can be realized.
  • the antenna gain is obtained by narrowing the directivity so that communication is possible even at a high carrier frequency.
  • urban cases such as the dense-urban model, it is possible to reduce the directivity to prevent transmission signals from mobile terminals from interfering with base stations other than those in communication. It is also important in terms of improvement.
  • interference can be reduced by setting the transmission power as follows.
  • the mobile terminal transmits a known sequence equivalent to sounding with the directivity of the first-stage beam and the second-stage beam, and transmits a known sequence equivalent to sounding with the omni directivity, in order to implement and maintain communication. Transmission may be performed intermittently in terms of time, frequency, and code.
  • the base station performs quality measurement, for example, SN measurement, not only on the first stage beam and the second stage beam but also on the omni beam. Even when the SN of the omni beam is low, the omni beam is completely synchronized with the communicating second stage beam, so that the SN of the omni beam can be accurately grasped.
  • the base station periodically notifies the mobile terminal of the SN measurement result of the signal transmitted by the mobile terminal using an omni beam (RRC / PUSCH or PUCCH).
  • the mobile terminal determines the omni-beam transmission power for transmitting the beam loss notification using the omni-beam SN received most recently.
  • the omni-beam SN measured by the base station is shown, but information other than the SN may be notified.
  • the mobile terminal may notify power information for transmitting a beam loss notification using an omni beam.
  • a beam loss notification can reach the base station by an SN that can be received by the base station. It is also effective to do.
  • the mobile terminal can determine the transmission power in consideration of the modulation multi-level number and coding rate during communication and the modulation multi-level number and coding rate used for the beam loss notification.
  • the mobile terminal monitors the SN of the base station with which it is communicating, detects that the base station signal has been lost, and indicates that the base station signal has been lost if the base station signal has been lost.
  • the link between the base station and the mobile terminal can be re-established quickly, and communication can be maintained.
  • Embodiment 1 for example, the following configuration is provided.
  • a communication system comprising a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication. More specifically, the mobile terminal performs radio communication using a beam. When the mobile terminal detects a beam lost state in which communication quality with the base station cannot be maintained, the mobile terminal transmits a notification of the beam lost state using a beam having a wider half-value width than before detection of the beam lost state.
  • a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication. More specifically, the mobile terminal performs radio communication using a beam. When the mobile terminal detects a beam lost state in which communication quality cannot be maintained with the first base station, the mobile terminal configures a dual connectivity with the first base station to notify the beam lost state. To the second base station. When the second base station receives the notification that the beam is lost, the second base station instructs the first base station to perform a beam redetection process with the mobile terminal.
  • FIG. The second embodiment relates to, for example, a technique for maintaining communication by changing a basic beam according to a change in communication status, and further relates to designation of a beam of a mobile terminal.
  • the base station when the beam forming is performed in two stages in both the base station and the mobile terminal, if the base station cannot identify the beam of the mobile terminal, the throughput is affected. Specifically, the base station receives data of a known sequence from the mobile terminal, acquires a transmission path estimation value from the received data, and determines a beam to be formed based on the transmission path estimation value.
  • the base station cannot determine what beam should be formed to improve the throughput.
  • the correlation between two beams is high and difficult to separate, it is effective to transmit the same data instead of transmitting different data for each beam. This is because the SN is improved and the throughput is improved.
  • the correlation between the two beams is low, the maximum throughput can be increased by transmitting different data for each beam, thereby improving the actual throughput.
  • an ID for identifying beams having different directions and half-value widths is assigned to the first stage beam.
  • IDs that can identify beams having different side lobe directions and peak powers may be assigned.
  • FIGS. 12 to 14 An example in which nine beams are formed as the first stage beam is shown in FIGS. 12 to 14, and an example of ID assignment corresponding to FIGS. 12 to 14 is shown below.
  • FIG. 12 to 14 show examples of the relationship between the directivity of the planar antenna and the full width at half maximum for the directivity in the range from -90 ° to + 90 °.
  • a dipole antenna, a helical antenna, or the like is used as a basic element, and a plurality of basic elements are arranged in a circular shape (in other words, a cylindrical shape) as in the example of FIG. Accordingly, it is possible to set the directivity and the full width at half maximum in the range from ⁇ 180 ° to + 180 °.
  • the mobile terminal changes its direction greatly with the passage of time, and the surroundings of the mobile terminal change. Therefore, it frequently occurs that the transmission path changes and does not return to the original state.
  • the mobile terminal detects the presence or absence of a large change in the transmission path by monitoring the SN of the known sequence signal from the base station, and assigns a different beam ID when determining that the transmission path has changed significantly. It is effective. According to this, it is possible to avoid erroneous use of transmission path information detected from the same beam ID before the transmission path is changed.
  • the number of beam IDs that can be set for the first stage beam is p, if these p beam IDs are used cyclically (1, 2,... .., P, 1, 2,..., P or more beam IDs can be secured.
  • the number of information bits can be limited even when the number of IDs increases, and the transmission efficiency can be increased.
  • the control information is overhead and is transmitted many times accompanying the data used by the user (U-plane data). Therefore, transmission efficiency can be improved by reducing the number of bits even by 1 bit.
  • the upper limit p of the number of IDs is notified from the base station using broadcast information or RRC at the time of channel setting (corresponding to RRC3Connection Reconfiguration in 3GPP).
  • IDs that are twice the number of IDs that can be set for the first stage beam are prepared (in other words, two sets of IDs are prepared), and another set of IDs is used when changing the beam ID. (In other words, toggling and using two sets of IDs) is also effective.
  • the ID used when changing the beam ID is notified from the base station using broadcast information or RRC at the time of channel setting (corresponding to RRC3Connection Reconfiguration in 3GPP).
  • the first method is a method in which the beam ID number is transmitted as data, and at that time, the beam ID data is transmitted by a beam having directivity and a half width corresponding to the beam ID to be transmitted.
  • Beam ID data may be attached to user data as a control channel (corresponding to PUCCH in 3GPP).
  • the base station can demodulate the control channel and extract the beam ID of the beam from a predetermined bit arrangement if the CRC is OK.
  • the second method does not transmit the beam ID as data, but associates the relationship between the beam ID and the beam ID transmission conditions (transmission timing, transmission frequency, etc.) by RRC (corresponding to RRC Connection Reconfiguration in 3GPP). ), And the base station identifies the beam ID based on the beam transmission conditions (that is, based on the detection timing, reception frequency, etc.).
  • the offset of the transmission period of the sounding signal transmitted by the mobile terminal with respect to the reference timing of the base station is set in advance by RRC.
  • the offset number for designating the offset is, for example, the number of symbols from the beginning of the frame.
  • the slot number may be used as an offset signal. An example is shown in the table below. An example of the cycle is also shown.
  • the transmission cycle it is also effective to change the transmission cycle according to the half width of the beam. For example, even if the half width is doubled, the total energy becomes the same if the period is halved.
  • the change speed of the transmission line may be monitored, and the set value may be changed according to the monitoring result.
  • a Doppler frequency measured for each mobile terminal in the base station may be used.
  • the base station or mobile terminal obtains information related to SN (SN change rate, SN variation (dispersion), etc.) from the opposite device, and uses such information as an index for monitoring the change in the transmission path. May be.
  • the third method uses an orthogonal code / pseudo-orthogonal code such as a Gold code or Hadamard code with a beam ID as seed as data to be transmitted. Since the sounding signals of a plurality of beams can be transmitted simultaneously, the amount of information for transmitting the beam ID, which is an overhead for U-plane data, can be reduced. Further, when the beam directions are different, the effect of SDM (Space Division Multiplex) can be taken into account for the sounding signals transmitted simultaneously, and the SN can be improved rather than simply code spreading.
  • the relationship between the seed of the orthogonal code / pseudo-orthogonal code and the beam ID is set in advance by RRC (corresponding to RRC Connection Reconfiguration in 3GPP), and the base station identifies the beam ID by the detectable seed.
  • a message prepared with IDs corresponding to multiples of the number of IDs that can be set for the first beam is transmitted.
  • the mobile terminal uses different sets of IDs when changing the beam ID.
  • the base station blindly detects a beam ID from a plurality of beam IDs, and if it detects that the beam ID has been switched, stops the process of integrating the transmission path information detected from the past beam ID. And discard, and calculate new transmission path information.
  • an orthogonal code / pseudo-orthogonal code such as a Gold code, a Hadamard code, or the like in which associations regarding transmission timing, transmission frequency, etc. are set in advance by RRC for each mobile terminal and the beam ID is set to seed.
  • RRC orthogonal code / pseudo-orthogonal code
  • the beam ID can be recognized by the base station and the mobile terminal.
  • the above method enables the base station to detect that the beam ID transmitted by the mobile terminal has changed. Therefore, it is also effective to determine that the beam is lost when the base station detects a change in beam ID without transmitting the beam loss notification (see St905 and St1001) described in the first embodiment.
  • a known sequence that is common to all mobile terminals and common to all beam IDs may be transmitted simultaneously.
  • the beam ID data and the common known sequence are used with resources whose timing is close enough that the transmission path does not change (timing immediately before transmitting the beam ID in the wireless format, etc.) You may send it.
  • the base station detects the presence / absence of a beam by judging signal quality using SN, etc., and performs beam ID identification only for mobile terminals that the base station permits transmission only when it is judged that there is a beam. To do. Thereby, the detection process of a base station can be reduced.
  • a known sequence common to all mobile terminals and common to all beam IDs is notified from the base station by broadcast information or RRC ⁇ Connection Reconfiguration equivalent in 3GPP.
  • a known sequence common to all beam IDs used in the mobile terminal may be transmitted, although it differs for each mobile terminal. Only when such a known sequence is detected, the base station performs beam ID identification of the mobile terminal. Thereby, the detection process of the base station can be further reduced.
  • a known sequence common to all beam IDs used in the mobile terminal is notified from the base station by broadcast information or RRCRRConnection Reconfiguration equivalent in 3GPP.
  • the mobile terminal is also effective to divide the mobile terminal into several groups, share resources such as timing and frequency within the group, and use a group ID for each group.
  • the relationship between the beam ID and the resource is set in advance by RRC so that the beam IDs in the mobile terminal are not the same.
  • RRC transmission timing, frequency, etc.
  • radio resources can be reduced by the statistical multiplexing effect.
  • the known sequence for the group ID is notified from the base station by broadcast information or equivalent to RRC Connection Reconfiguration in 3GPP.
  • a combination of two or more of a known sequence common to all mobile terminals and common to all beam IDs, a known sequence common to all beam IDs used in the mobile terminal, and a known sequence for group ID can be further reduced.
  • a communication system comprising a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication. More specifically, the mobile terminal performs wireless communication by a two-stage beam forming method using a multi-element antenna. The mobile terminal transmits information for identifying the attribute of each beam in the first stage to the base station.
  • Embodiment 3 relates to interference countermeasures for other base stations, for example.
  • the beam forming mainly in the uplink has been described.
  • beam forming on the mobile terminal side will be described in order to improve downlink (base station ⁇ mobile terminal) throughput.
  • the base station acquires downlink transmission path information from the received uplink signal using reversibility, calculates a precoding weight based on the obtained downlink transmission path information, and uses the calculated precoding weight as downlink transmission data. It is known that the method of multiplying is effective in improving the throughput. However, since the data transmitted in this way cannot take into account interference components from other base stations, there arises a problem that the expected throughput cannot be obtained.
  • the first method is a method in which interference information from other base stations other than the communicating base station is measured by the mobile terminal, and the information is fed back to the communicating base station.
  • the mobile terminal uses the degree of freedom of the antenna of the mobile terminal by post coding or the like to reduce the interference from other base stations as much as possible by transmitting the transmission data transmitted by multiplying the precoding weight by the communicating base station. Receive.
  • post-coding or the like is performed, for example, when the degree of freedom of the antenna is insufficient, or signals from base stations in communication (including reflected waves) and signals from other base stations not in communication Are coming from similar directions, interference from other base stations not communicating remains.
  • the shortage value for the required SN or the amount of interference from other base stations not communicating is fed back to the communicating base station.
  • the base station in communication increases the transmission power based on the fed back information, thereby improving the throughput.
  • the total transmission transmitted by the communicating base station compared to the case where the transmitting power is uniformly increased at the communicating base station. Electric power can be reduced.
  • the information to be fed back is notified from the mobile terminal to the base station in accordance with RRC measurementmeasurereport in 3GPP. It is not a report of the reception power of surrounding base stations, specifically, data transmitted by a base station in communication with a beam with an appropriate directivity and received with an appropriate directivity beam formed by a mobile terminal
  • the point of measuring the amount of interference from other base stations not communicating is different from the measurement report used in the 3GPP neighboring cell monitor for handover or the like.
  • the mobile terminal detects the PSS and SSS of another base station that is not in communication, the mobile terminal stores the detected timing, frequency, etc. for each cell ID, and moves the signal to and from the base station in communication It measures how much interference will be received if it is received with an appropriately directional beam formed by the terminal.
  • the information to be fed back may be a message element attached to an RRC measurement report in 3GPP.
  • RRC has a longer reflection period, but it is effective because it can compensate for the average value of interference components from other base stations that are not communicating.
  • the method of compensating for the average amount of interference from other base stations not communicating is shown using the measurement report equivalent.
  • the shortage value for the required SN or the amount of interference from another base station not in communication is fed back to the base station in communication using the PUCCH or L1 control signal in 3GPP, the feedback is made in a short time. Can do. For this reason, the fluctuation
  • a transmission power increase / reduction request command for example, 1: 1 dB increase, 0: 1 dB decrease, or +1: increase required, 0: change not required, -1: decrease possible
  • the command is fed back. This is effective in reducing the amount of information to be fed back.
  • the second method is information about how much interference is received when receiving a beam with an appropriate directivity formed by a mobile terminal with a communicating base station (corresponding to RRC measurementmeasurereport in 3GPP). Information) is used to adjust so that data transmission from a plurality of base stations is not performed simultaneously.
  • the base station in communication does not want to use the base station of the cell ID notified from the mobile terminal or wants to refrain from using it as much as possible (timing, frequency, spreading code, resource block, etc.) Is notified by an inter-base station message.
  • the inter-base station message may be transmitted via an upper device of the base station.
  • the base station in communication transmits data to the mobile terminal using the resource notified by the inter-base station message.
  • inter-base station message may be transmitted via an upper device of the base station.
  • the base station in communication transmits data to the mobile terminal while avoiding the resources notified by the inter-base station message as much as possible.
  • the third method is a method for solving the above problem by forming the first stage beam by the mobile terminal as follows.
  • the mobile terminal does not transmit the sounding signal as it is with the first-stage beam in which the transmission direction and the half width are simply set, but transmits the signal constituted by the following steps.
  • A1 First-stage beam (receives known sequence data) so that the main beam is directed to the communicating base station and null is directed to other base stations other than the communicating base station. Beam).
  • a base station other than the base station that is in communication only a base station that uses received power that is greater than the magnitude that affects communication may be selected. For example, a required SN corresponding to the received modulation method, coding rate, etc. is set as a threshold value.
  • the mobile terminal is different from (A1) so that, in addition to the formation of the beam of (A1) above, a null is directed to another base station other than the base station in communication Another directional first stage beam is formed.
  • the mobile terminal (A1) directs null toward a base station other than the base station in communication.
  • the mobile terminal (A2) directs null toward a base station other than the base station in communication.
  • another first-stage beam having a directivity different from that of (A2) is formed.
  • a signal composed of the following steps may be transmitted.
  • the mobile terminal tentatively determines the number of beams to be set in the multipath direction from the received signal of the communicating base station.
  • (B2) A beam is formed so that the main beam is directed to the multipath of (B1) and a null is directed to another base station other than the base station in communication. If the inverse matrix can be calculated, beam forming is completed.
  • the base station performs precoding as usual.
  • the mobile terminal provides one beam toward the base station a as the first stage beam for transmitting the known sequence (see the beam indicated by the broken line).
  • the beam is null toward the base station b.
  • the other beam points null to both base station a and base station b.
  • the directivity of the beam including the multipath of the base station a is improved.
  • null is suitable for the base station b, the mobile terminal can be prevented from receiving interference from the base station b. As a result, the expected throughput can be obtained.
  • Embodiment 3 for example, the following configuration is provided.
  • a communication system comprising a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication. More specifically, when the mobile terminal communicates with the first base station but does not communicate with the second base station, the mobile terminal transmits the second base to the transmission signal from the first base station. The degree of interference exerted by the station is measured, and the measurement result is transmitted to the first base station. The first base station changes the transmission power of the signal transmitted to the mobile terminal based on the received measurement result.
  • a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication. More specifically, when the mobile terminal communicates with the first base station but does not communicate with the second base station, the first base station transmits data from the first base station to the mobile terminal. A communication condition for suppressing interference with data transmission by the second base station is adjusted, and a data transmission according to the adjusted communication condition is requested to the second base station.
  • a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication. More specifically, the mobile terminal performs wireless communication by a two-stage beam forming method using a multi-element antenna. If the mobile terminal communicates with the first base station but does not communicate with the second base station, the mobile terminal has a main beam directed toward the first base station and null with respect to the second base station. The first beam that is directed and at least one second beam that is null-oriented with respect to the second base station and has a different directivity from the first beam are formed as the first stage beam.
  • a communication system including a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication. More specifically, the mobile terminal performs wireless communication by a two-stage beam forming method using a multi-element antenna.
  • the mobile terminal communicates with the first base station but does not communicate with the second base station, the mobile terminal is directed to the second base station with the main beam directed to the multipath direction of the first base station.
  • at least one beam having a null direction is designed by adjusting the set number of multipaths, and the designed beam is formed as the first stage beam.
  • Embodiment 4 relates to, for example, handling of whether or not reversibility is possible.
  • the fourth embodiment provides a communication technology that enables setting whether or not reversibility is supported for each frequency band, and allows frequencies that can be reversible even if reversibility is not possible in all bands. It shows that high-speed communication is possible in the band.
  • FIG. 17 is a sequence diagram illustrating an example in which the setting of whether to support reversibility for each frequency band is performed at the time of channel setting.
  • the mobile terminal transmits reversibility supportability information for each frequency band as UE-capability to the base station.
  • the reversibility supportability information is transmitted in the equivalent of RRC Connection Setup Complete in 3GPP (corresponding to a response to a channel setting request or a change request).
  • the base station determines whether or not reversibility can be supported for each cell ID and each frequency band and the corresponding transmission efficiency, and starts preparation at the base station. To do. Also, the base station notifies the mobile terminal of setting information corresponding to precoding for each frequency band, corresponding to RRC Connection Setup (step St1606).
  • the 2 GHz band is used only for control signals and a wide bandwidth (15 GHz, 28 GHz, 60 GHz, etc.) different from 2 GHz is used for U-plane wideband transmission with a multi-element antenna, it is reversible to 2 GHz. Is not necessary, and a simple transceiver is used. In order to ensure reversibility, calibration is required to match the transmission and reception beam patterns, and it is necessary to match the frequency characteristics of transmission and reception. An inexpensive mobile terminal can be realized.
  • the base station determines the correspondence to the reversibility based on the UE-capability for each frequency band transmitted from the mobile terminal and the capability for each ID of the base station itself. Transmission path estimation using reversibility is used only in a frequency band in which both the base station and the mobile terminal can support reversibility. Precoding is also performed using this channel estimation value.
  • the base station instructs the base station to transmit the channel estimation value measured by the mobile terminal, and the base station performs interference cancellation such as precoding.
  • the mobile terminal Based on the transmission path estimation value measured by the mobile terminal, the mobile terminal sets how the phase and amplitude of each beam of the base station are set to reduce interference.
  • the base station instructs the mobile terminal to transmit the result to the base station, and the base station performs precoding based on the acquired information.
  • the base station does not perform processing for beam interference reduction such as precoding.
  • the base station specifies information (frequency, time (period), resource block position, etc.) for allowing the mobile terminal to transmit sounding by using the equivalent of RRC Connection Setup.
  • the base station designates a radio format for reporting the downlink transmission path estimation value measured by the mobile terminal, a measurement cycle, and the like, corresponding to RRC Connection Setup. Instead of transmitting sounding, the mobile terminal notifies measurement information according to the instruction of the base station.
  • the base station transmits the phase and amplitude information for each beam of the base station or the index information indicating the combination of the phase and amplitude for each beam in any radio format and cycle. Specify whether to report from RRC Connection Setup. Instead of transmitting sounding, the mobile terminal notifies information according to the instruction of the base station, that is, information on the phase and amplitude for each beam, or index information on a combination of phase and amplitude for each beam.
  • step St1609 is not calculated. Therefore, step St1611, that is, U-plane data transmission with precoding is not performed.
  • the reversibility requires different performance depending on the information transmission efficiency.
  • the information transmission efficiency depends on MCS (Modulation and Coding Scheme), the corresponding number of layers (the number of streams of signals transmitted at the same frequency at the same time), and the like.
  • MCS Modulation and Coding Scheme
  • the base station can support a scheme up to 64QAM and a coding rate of 3/4
  • the mobile terminal can support a scheme of up to 256QAM and a coding rate of 5/6
  • a practical method is up to 64QAM and a coding rate of 3/4.
  • the base station calculates a precoding weight using the sounding signal in step St1609 (step St1610), and thereafter, the base station transmits downlink data after performing precoding.
  • the base station when transmitting data before step St1610, the base station transmits data without precoding.
  • the reversibility supportability information as UE-capability of the mobile terminal by transmitting the reversibility supportability information as UE-capability of the mobile terminal from the mobile terminal to the base station, it is possible to support transmission even when the reversibility supportability of the mobile terminal and the base station is mixed. Precoding can be performed efficiently.
  • by providing reversibility supportability information for each frequency band it is possible to perform precoding with compatible transmission efficiency even if reversibility supportability is mixed for each frequency band in one mobile terminal. it can.
  • FIG. 18 to FIG. 19 are sequence diagrams for explaining an example of setting whether or not to support reversibility for each frequency band at the time of handover.
  • 18 and 19 are connected at the position of the boundary line BL. Capability exchange corresponding to the frequency band that can be used at the destination (handover destination) is performed, and reversibility up to the lower value of transmission efficiency is used, or transmission path estimation is performed without using reversibility. Is determined by the base station. After the notification of the determination content, communication of U-plane data is started.
  • the source base station uses Handover Required (step St1702).
  • the SGW serving gateway.
  • the SGW notifies the handover destination base station of the handover request according to the contents of Handover Required (step St1703).
  • the SGW receives a notification from the destination base station that the handover is possible (step St1704)
  • the SGW notifies the source base station to that effect (step St1705).
  • the source base station notifies the SGW of information on whether or not the mobile terminal can handle reversibility, information on compatible MCS and the number of layers as information on the mobile terminal (step St1706).
  • the information to be notified is information for each frequency band.
  • the SGW transfers the notified information to the movement destination base station (step ST1707). Therefore, if the source base station directly transmits Status transfer to the destination base station, it is effective because the set time can be shortened.
  • the movement-destination base station determines whether or not the reversibility can be supported, the MCS and the number of layers that can be supported (step St1708), and the setting information on whether or not to support the precoding for each frequency band to be used as a result The station is notified (step St1709).
  • the subsequent steps St1710 to St1715 are the same as the example in FIG. 17 (example in which the setting of whether or not to support reversibility for each frequency band is performed at the time of channel setting).
  • a communication system comprising a mobile terminal and a base station connected to the mobile terminal so as to be able to perform wireless communication. More specifically, the mobile terminal is configured to be able to perform reversible use transmission path estimation, which is transmission path estimation using reversibility of the transmission path, for each frequency band.
  • the mobile terminal transmits, to the base station, reversibility availability information indicating, for each frequency band, whether or not reversible utilization transmission path estimation is possible.
  • the base station uses reversible utilization transmission path estimation in a frequency band where both the mobile terminal and the base station can perform reversible utilization transmission path estimation based on the reversibility supportability information of the mobile terminal. To communicate with the mobile terminal.

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Abstract

La présente invention concerne une technique grâce à laquelle une bonne qualité de communication peut être assurée. Un système de communication est pourvu d'un terminal mobile et d'une station de base connectée au terminal mobile d'une manière pouvant communiquer sans fil. Le terminal mobile réalise une communication sans fil à l'aide d'un faisceau. Le terminal mobile, lors de la détection (St904) d'un état de perte de faisceau dans lequel la qualité de communication avec la station de base ne peut pas être maintenue, transmet une notification de l'état de perte de faisceau à l'aide d'un faisceau ayant une largeur de demi-valeur supérieure à celle avant la détection de l'état de perte de faisceau (St905).
PCT/JP2018/007132 2017-03-21 2018-02-27 Système de communication Ceased WO2018173646A1 (fr)

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CN202310166715.3A CN116170045A (zh) 2017-03-21 2018-02-27 通信系统
EP18770534.8A EP3605867A4 (fr) 2017-03-21 2018-02-27 Système de communication
CN202310155307.8A CN116137545A (zh) 2017-03-21 2018-02-27 通信系统
EP23170358.8A EP4236105A3 (fr) 2017-03-21 2018-02-27 Système de communication
JP2019507475A JPWO2018173646A1 (ja) 2017-03-21 2018-02-27 通信システム
CN201880017350.5A CN110431758A (zh) 2017-03-21 2018-02-27 通信系统
US16/484,899 US10785661B2 (en) 2017-03-21 2018-02-27 Communication system
US16/992,217 US11483718B2 (en) 2017-03-21 2020-08-13 Communication system
US17/941,143 US20230007505A1 (en) 2017-03-21 2022-09-09 Communication system
JP2022180092A JP7499822B2 (ja) 2017-03-21 2022-11-10 通信システム、移動端末およびマスター基地局
US18/237,281 US12137356B2 (en) 2017-03-21 2023-08-23 Communication system, user apparatus and base station

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